The invention relates to a bag for insertion into a cavity of a silencer intended for sound damping, a set of such bags, a silencer with such bags and corresponding methods for making the aforementioned.
A silencer is a device for reducing sound emissions. Various types of silencers exist, which reduce the generated sound power based on different mechanisms of action. An absorption silencer contains porous material, usually rock wool, glass wool or glass fibers, which partially absorbs the sound energy, i.e. converts it into heat. The effect of sound absorption is amplified by the multiple reflections. The invention relates particularly to such silencers. Such silencers for internal combustion engines, especially for passenger cars or trucks, have a perforated inner tube for the passage of the exhaust gases. This inner tube is routed in a cover impervious to air, dirt and moisture, thus forming a cavity is between the inner tube and the cover. This cavity is filled with a sound-damping or sound-absorbing filling, which must be heat-resistant. Since filling the cavity is complicated, prefabricated flexible or more or less rigid elements with a sound-absorbing filling are used instead.
For example, dimensionally stable molded parts constructed from glass fibers, basalt wool and multiple components are known which contain flammable components for shape retention, which burn at the first use of the silencer.
Bags are known for insertion into a cavity of a silencer intended for sound damping or absorption with a completely enclosed cover, with a sound-damping or sound-absorbing filling, wherein the cover is composed of plastic films or webs, which are welded after filling.
WO 2005/049982 discloses a bag for insertion into a cavity of a silencer intended for sound damping or sound absorption with a knitted tubular cover and a sound-damping or sound-absorbing filling, wherein the cover is made of glass fibers. The filling is introduced into the cover which is then closed at its respective ends. It is not disclosed to produce certain 3D shapes.
DE 203 05 409 U discloses a bag for insertion into a cavity of a silencer intended for sound damping or sound absorption having a tubular non-heat resistant cover and a sound-damping or sound-absorbing filling. The filling is introduced into the cover which is then closed at its respective ends. It is not disclosed to produce certain 3D shapes. The cover combusts during the operation of the silencer.
U.S. Pat. No. 6,068,082 discloses a grid-like element for insertion into a cavity of a silencer intended for sound damping or sound absorption having a heat-resistant cover and with a sound-damping or sound-absorbing filling. The filling is introduced into the cover, whereafter the cover is sealed.
GB 2 267 731 discloses a flexible bag for insertion into a cavity of a silencer intended for sound damping or sound absorption with a fusible cover and a sound-damping or sound-absorbing filling. It is disclosed, among other things, to place the bag around the inner tube of the silencer.